Art of purifying nitrocellulose.



No. 762,757. PATENTED JUNE 14, 1904.

' F. I. DU FONT.

7 N0 MODEL.

' w rzncds'zfial out M/aja j? BY W Arm/M Patented une 14, 1904.

UNITED STATES PATENT 'OFFICE.

FRANCIS I. DU PONT, OF WILMINGTON, DELAWARE.

ART OF PURIFYING NITROCELLULOSE.

SPECIFICATION forming part .of Letters Patent N0. 762,757, dated June 14, 1904.

Application filed March 5, 1904. Serial No. 196-719. (No specimens.)

To all whom it may concern:

Be it known that LFRAnoIs I. DU PoNr, a citizen of the United States,and a resident of Wilmington, in the county of Newcastle and State of Delaware, have invented new and useful Improvements in the Art of Purifying Nitrocellulose, of which the following is a full, clear, and exact description.

My invention relates to improvements in the art of purifying nitrocellulose and analogous substances, my more particular object being to dislodge impurities which affect the stability of the nitrocellulose and also to remove any gaseous impurities which may be occluded within the material owing to its organic structure.

Reference is to be had to the accompanying drawing, forming a part of this specification,

' in which the figure represents one form of apparatus suitable for carrying out my process.

I do not limit myself to this or to any other particular form of apparatus.

A tank 1 is mounted on a base 2, provided with a conical bottom 3 and with an air-tight cover 4, the cover and bottom being secured in position by means of bolts 5 so as to render the apparatus gas-tight. A pipe 6 is connected with a pump ,7 and a pipe 8 is connected with the top 4 and with the pump v7,

forming through this pump a continuous way whereby air may be passed when the pump is in action.* The tank 1 is provided with a pipe 9, provided with a hand-valve 10., and also with pipes 11 and 13, having hand-valves 12 and 14. The tank 1 is partially filled with water 15. Another tank, 16, contains an agitator l7 and a screen 19. This tank is partly filled with nitrocellulose 18 and is fitted with a valve 20. A pulley 21 is provided to drive the agitator 17 My process is carried out as follows: The tank 1 is partially filled with water 15 by opening the valve 14 and admitting the water through the pipe 13. Compressed air or other gas is forced through the pipe 11 into the upper part of the tank at a considerable pressure say one hundred pounds per square inch. I find that this pressure gives good results. However, this may be varied according to conditions. When air is used, it is continuously 7 is next started and sucks the air through the pipe 8 and forces it back into the tank again through the pipe 6*? This operation is kept up continuously until all parts of the liquid are saturated with gas. The valve 10 is next turned, and as much of the liquid as is desired is emptied irito the tank 16 through the pipe 9, this tankhaving already in it nitrocellulose 18 to be purified. This material is kept in suspension by the agitator 17.

The liberation of the liquid and subsequent reduction of atmospheric pressure cause the air absorbed within the water to expand suddenly, the result being that the impurities within the nitrocellulose-are dislodged and of course serve to render the water more or less impure. The water is then drawn off through the discharge-valve 20, the screen 19 keeping the nitrocellulose from escaping at the same time.

My theory of the action of the air is that the compression of the air renders the action out the entire substance of the nitrocellulose and dislodges impurities which apparently cannot be reached as well in any-other manner. Of course the operation may be repeated again and again until the desired degree of purification is reached.

Having thus described my invention, I claim as new and desire to secure by Letters Patent 1. An improvement in the art of purifying nitrocellulose and like substances, which consists in subjecting a liquid to the action of a gas under pressure for the purpose of causing said liquid to absorb a quantity of said gas, and transferring said liquid containing said gas into a vessel containing the nitrocellulose or like substance to be purified, before the gas has time to escape, so that same escapes through said nitrocellulose or other substance.

2. An improvement in the art of purifying nitrocellulose and like substances, which conslsts in transferring the water containing av nitrocellulose and like substances, which consists in bringing the same into contact with a quantity of water, and admixing therewith another portion of water holding a gas in solution before said gas has time to escape from second portion, so as to permit said gas to escape through the nitrocellulose or substance to be purified.

In testimony whereof I have signed my name to this specification in the presence of two subscribing Witnesses.

FRANCIS I. DU PONT.

Witnesses:

HENRY DRURY, D. M. MACDONALD. 

